Unite said the next step will be to consult members over the timing and nature of possible strike action, as it urged Wood Group to re-open the talks which collapsed recently.

Ire was stirred amid accusations of lower pay, longer hours and more demanding work schedules. North Sea oil firms have been forced to make cuts due to low oil prices, which have eaten into their profitability.

"The move by Shell to engage a scab labour workforce through various agencies to cover any potential industrial action is extremely disturbing," he warned.

Paul Goodfellow, Shell UK and Ireland upstream vice president, said the oil major was disappointed that the dispute has reached this stage.

"We hope that Wood Group’s employees and management can resolve their issues. Our priority is to ensure that the safety of our people and assets will not be compromised during any industrial action."

Dave Stewart, chief executive for Wood Group’s eastern region business unit, added: "Reaching a resolution, which meets our mutual goal of safeguarding these jobs in the North Sea now and in the future remains our commitment and we will continue to engage fully in discussions with our employees and the unions."